Treatment of Phlegmon
For appendiceal phlegmon, non-operative management with antibiotics (and percutaneous drainage if an abscess is present) is the recommended first-line treatment when advanced laparoscopic expertise is unavailable, while laparoscopic appendectomy is preferred when such expertise is available. 1
Initial Treatment Approach
The optimal treatment strategy depends critically on the availability of advanced laparoscopic surgical expertise and the specific clinical presentation:
When Laparoscopic Expertise is Available
Laparoscopic appendectomy is the treatment of choice for appendiceal phlegmon or abscess when advanced laparoscopic expertise is available, with a low threshold for conversion to open surgery. 1 This approach offers several advantages:
- Fewer readmissions compared to conservative management (3% versus 27%, P = 0.026) 1
- Fewer additional interventions required (7% versus higher rates with conservative treatment) 1
- Shorter hospital stay by approximately 1 day compared to conservative treatment in high-quality RCTs 1
- Lower incidence of bowel resection (3.3% vs 17.1%, P = 0.048) when compared to patients who fail non-operative management 1
Important caveat: Patients undergoing laparoscopic surgery have a 10% risk of bowel resection and 13% risk of incomplete appendectomy, requiring experienced surgical judgment 1
When Laparoscopic Expertise is Not Available
Non-operative management with antibiotics and percutaneous drainage (if accessible) is recommended for complicated appendicitis with periappendicular abscess or phlegmon. 1 This approach:
- Succeeds in over 90% of patients with appendicular abscess or phlegmon 1
- Requires percutaneous drainage in only 19.7% of cases 1
- Fails in 7.2% of patients, necessitating operative intervention 2
- Associated with 25.4% failure rate in patients with appendiceal abscesses who received drains, with older age and later drain placement predicting successful treatment 1
Critical warning: All patients who fail non-operative management (25.7%) typically require open operation, with most requiring bowel resection 1
Antibiotic Therapy
For all patients with phlegmon, broad-spectrum antibiotics are essential regardless of whether surgical or non-operative management is chosen 1, 3
Special Considerations
Crohn's Disease-Related Phlegmon
For abdominal phlegmon in penetrating Crohn's disease, combination therapy with antibiotics and anti-TNF antibody therapy is safe and effective after infection has been controlled. 3 This approach avoids surgical resection in most cases, though anti-TNF therapy should only be initiated after adequate antibiotic treatment 3
Interval Appendectomy Decision
Routine interval appendectomy is NOT recommended after successful non-operative management in most patients 1:
- Risk of recurrence is only 7.4% after successful non-operative treatment 1, 2
- Interval appendectomy carries 12.4% morbidity 1
- Cost-effectiveness favors observation over routine interval appendectomy, reserving surgery only for patients with recurrent symptoms 1
Exception: For patients ≥40 years old with complicated appendicitis, both colonoscopy and interval full-dose contrast-enhanced CT scan are recommended due to 17% rate of neoplasms found in this age group 1, 4
Key Clinical Pitfalls to Avoid
- Do not delay percutaneous drainage when technically feasible for appendiceal abscess, as later drain placement predicts treatment failure 1
- Do not attempt immediate surgery for appendiceal phlegmon/abscess without advanced laparoscopic expertise, as this is associated with significantly more complications (wound infections, abdominal/pelvic abscesses, ileus/bowel obstructions, and re-operations) compared to conservative treatment 1
- Do not fail to follow up patients ≥40 years old after non-operative management, as they have higher risk of underlying malignancy 4
- Maintain low threshold for conversion to open surgery during laparoscopic approach 1